Consider a Bernoulli process, with arrival probability at each time slot equal to . An observer arrives at time slot 10 and sees that no arrival took place in that slot. A passerby informs the observer that there was exactly one arrival during the preceding two time slots (i. e., time slots 8 and 9) but has no additional information about which of the two it was. Let be the number of time slots starting from the time slot of the last arrival (before slot 10) and until the time slot where the next arrival comes. For example, if the last arrival came at time 8 and the next arrival comes at time 13, is the number of slots in the interval , so that . (Enter a numerical expression or a decimal accurate to at least 3 decimals places.) Find the probability that .